The present invention relates to an automatic engine stop and restart system for vehicles, and in particular to an automatic engine stop and restart system that executes an automatic engine stop that is so-called an idle stop when predetermined conditions such as continuous stoppage of a vehicle are satisfied and an automatic engine restart when conditions for restarting the engine are satisfied. The present invention further relates to a method for controlling an automatic engine stop and restart.
An automatic engine stop and restart system has been proposed that automatically stops an engine during stoppage of a vehicle and thereafter automatically restarts the engine at start of a vehicle for the purpose of, for example, preventing emission of an exhaust gas during stoppage of the vehicle at a crossing in the street.
The so-called idle stop technique is widely used in hybrid vehicles that use jointly an engine and an electric motor as a power source for driving the vehicles. In such vehicles, various idle stop techniques such as a technique for stopping an engine and driving a vehicle only by an electric motor at particularly low-speed running of the vehicle and automatically restarting the engine when the vehicle speed reaches a predetermined value, are utilized.
Further, Japanese Patent Provisional Publication No. 2001-55941 discloses an automatic engine stop and restart system that automatically restarts the engine even when stoppage of the engine that is not due to an automatic engine stop control, i.e., engine stall due to an erroneous operation of the engine or due to excessively rapid braking by a driver is caused, similarly after an automatic engine stop control, by determining whether conditions of an automatic engine restart are satisfied. Specifically, in case stoppage of the engine that is not due to the automatic engine stop control is caused, the engine is restarted by operating a starter motor or a corresponding motor generator, while performing a predetermined operation such as depression of the clutch pedal or release of depression on the brake pedal.
However, the automatic engine stop and restart system disclosed in the above described publication is adapted to automatically restart the engine when the engine speed is zero and predetermined conditions (e.g., depression of the clutch pedal) are satisfied and to detect entirely nothing about whether a manual starting operation is performed by a driver at the start of driving of the vehicle. Accordingly, there can occur such a case in which the engine is automatically started unexpectedly if, for example, predetermined conditions are satisfied when the driver gets on the vehicle and turns the ignition key switch ON but has not yet executed a manual starting operation (e.g., cranking by turning the ignition key switch into the start position), thus causing a problem that the driver has a strange feeling.
Further, the system of the above-described publication executes an automatic engine restart with the condition that the engine speed is zero. Thus, in case of engine stall that is not intended by the driver, the engine is always stopped once completely and immediately thereafter cranking is started to automatically restart the engine. Accordingly, the driver also has a strange feeling at the time of engine stall.
It is accordingly an object of the present invention to provide an automatic engine stop and restart system for a vehicle that is free from the above noted problems inherent in the prior art system.
It is another object of the present invention to provide a method for controlling an automatic engine stop and restart that is of the foregoing character.
To accomplish the above object, there is provided according to an aspect of the present invention an automatic engine stop and restart system for a vehicle comprising a controller for controlling an automatic stop and restart of an engine in accordance with a driving condition of the vehicle, the controller including a control section for automatically restarting the engine when an engine speed is lowered so as to be equal to or lower than a predetermined engine speed under a condition that a vehicle main switch is ON and predetermined automatic engine stop conditions are not satisfied, and a control section for inhibiting the automatic restart of the engine before a first manual engine start after the vehicle main switch has been ON is completed.
According to another aspect of the present invention, there is provided an automatic engine stop and restart system for a vehicle comprising means for automatically restarting the engine when an engine speed is lowered so as to be equal to or lower than a predetermined engine speed under a condition that a vehicle main switch is ON and predetermined automatic engine stop conditions are not satisfied, and means for inhibiting an automatic restart of the engine before a first manual engine start after the vehicle main switch has been ON is completed.
According to another aspect of the present invention, there is provided a method for controlling an automatic stop and restart of an engine in accordance with a driving condition of a vehicle, comprising automatically restarting the engine when an engine speed is lowered so as to be equal to or lower than a predetermined engine speed under a condition that a vehicle main switch is ON and predetermined automatic engine stop conditions are not satisfied, and inhibiting the automatic restart of the engine before a first manual engine start after the vehicle main switch has been ON is completed.